A monkey etched into the Nazca Desert as seen from the air. Photo: Maria Reiche

Another of Peru's great mysteries, the Nazca Lines have long baffled archaeologists and scientists alike.

The Nazca Lines are etched on a large, arid coastal plain 400km south of Lima. They cover 645 square kilometres of rocky desert that's also happens to be one of the driest places on earth.

Thought to be constructed sometime between 200BC and 600AD, the artists would have had no reference to see what their designs looked like. It's only once you take to the air that the lines and shapes take form. Suddenly monkeys, spiders and birds jump out from the strange patterns in the Nazca Desert. It's kind of spooky.

Google "Nazca Lines" and you'll find a myriad of otherworldly explanations: the lines are a landing strip for returning aliens; they were built by the Inca who are actually aliens; they're a map of underground water supplies; or they are used for astronomical rituals.

Some US researchers have recreated the patterns using basic surveying tools available to the Nazca people, which may cover the how, but still no-one really knows why.

The lines were made by removing the darker-coloured pebbles covering the plain to expose the light-coloured earth underneath. With no water to erode them or sand to cover them, the lines have remained well-preserved.

The best way to see the lines is by air. You can travel the 600km to the small township of Nazca or make a trip only 220km south of Lima (three hours by bus) to the quaint coastal village of Pisco where tour operators also offer flights.

Unfortunately, even the Nazca Lines have not escaped climate change. Extremely high rainfall in the region in early February 2007, caused by El Nino, has noticeably eroded the lines. Don't wait too long if you want to see this wonder.